$re = '/^\d{1,3} (?<PartNum>.*?)\n(?<Description>(?:.|\n)+?)(?=^\d{1,3}|\Z)/mi';
$str = '1 HUY-12
Description line 1 for the HUY-12
2 JIU-14
Description line 1 for the JIU-14
This one has 2 lines of description
3 KOI-10
Description line 1 for the KOI-10
Second description line
Third description line
4 GYT4
Description line 1 for the GYT4';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php